Roseanne Barr’s Tweets Didn’t Come Out of Nowhere

Roseanne Barr found herself at the center of a firestorm on Tuesday, after a racist post on her Twitter account compared Valerie Jarrett, an African-American and a former special adviser to former President Barack Obama, to an ape. Her show, “Roseanne,” which had been a ratings hit when it was revived this spring, was swiftly canceled by ABC, scrapping plans for what would have been its 11th season over all.

Ms. Barr has expressed support several times for the fringe conspiracy theory “QAnon.” At the end of March, a now-deleted post from Ms. Barr read: “President Trump has freed so many children held in bondage to pimps all over this world. Hundreds each month. He has broken up trafficking rings in high places everywhere. notice that. I disagree on some things, but give him benefit of the doubt-4 now.”

As the journalist Will Sommer explained: “QAnon believers are convinced that the world is run by a nefarious deep state cabal of Democrats, celebrities and intelligence community figures (many of whom, they claim, are pedophiles). Trump is about to take them all down, in their telling, often with sealed indictments that are hidden from the public.”

Also on Tuesday, Ms. Barr falsely referred to George Soros, the liberal financier long loathed by many on the right, as a Nazi collaborator who turned in fellow Jews in wartime Hungary. The day before, she wrote that Mr. Soros planned on overthrowing the government and that Chelsea Clinton was married to a Soros relative, which Ms. Clinton responded to.

There’s way more where that came from. At the end of March, Ms. Barr deleted a post saying that David Hogg, an outspoken survivor of the Parkland shooting, gave a Nazi salute.

Days later, ABC announced it was renewing “Roseanne” for another season.

There was the time last year when she retweeted an Infowars piece that falsely said there were 5.7 million undocumented immigrants who voted in the 2016 election, and she has pushed conspiracy theories about Seth Rich, a Democratic National Committee staff member who was shot dead in 2016 in Washington.

She said that she hoped the University of California, Davis, “gets nuked” after the student body voted in 2015 to recommend the university divest from businesses associated with Israel. In 2013, Ms. Barr said Susan Rice, the former national security adviser, “is a man with big swinging ape balls.”

Even when she is not offending people or pushing conspiracy theories, Ms. Barr is busy on Twitter, with supportive messages about President Trump, retweets of diatribes against the media, links to pro-Israel articles and retweets of fan support for her show. She is even conciliatory at times.

Ms. Barr said she was “leaving Twitter” after the firestorm over her posts on Tuesday. It wasn’t the first time she said she was taking a break from the platform in recent months. She also said she would do so at the end of 2017.